Characterisation of Plasmodium falciparum aspartic protease inhibition by piperidine derivatives

Piperidine derivatives are reported to exhibit a variety of pharmacological activities. In this article, synthesis and aspartic protease inhibitory activity of three nitrophenacyl derivatives of N-methyl-4-hydroxy piperidine are reported. Enzyme assays showed that the attachment of a nitro group in the benzene ring plays an important role in the inhibition of plasmepsin-II of Plasmodium falciparum. The compound 1-methyl-1-(4'-nitrophenacyl)-4-hydroxypiperidinium bromide (3), consisting of a nitro group at the para position, was the most active at the concentration of 1.0?μM. The activity of the compounds was evaluated through the observed orientation and diagrammatic representation of nitrophenacyl derivatives of 4-hydroxy piperidine.     

Application of Self-Assembled Monolayers in the Preparation of Solid-Phase Microextraction Coatings

Self-assembled monolayers (SAMs) of polyaminithiophenol (PATP) were used as a covalent bonded coating for solid-phase microextraction (SPME). Thiolated aniline-analog monomers (mixture of 2- and 3-aminothiophenols, 2/3-ATP) were anchored on the gold surface and then electropolymerized. Due to the strong S?CAu bond, thiol-terminated coating on the gold surface was very stable. The proposed covalent bonded coating showed higher mechanical (re-usability up to 100 times) and thermal stability (up to 320???C) than non-covalent bonded polyaniline coating (re-usability up to 20 times and thermal stability up to 250???C). The extraction capability of the proposed fiber for the extraction of five polycyclic aromatic hydrocarbons (PAHs), including phenanthrene, anthracene, pyrene, 9,10-dimethylanthracene and benzo[??]anthracene was examined. The effects of different parameters influencing the extraction efficiency of analytes including extraction temperature, extraction time, ionic strength, stirring rate and sample volume were examined and optimized. Linear ranges of 1?C250???g?L^?1 for phenanthrene and anthracene, and 1?C100???g L^?1 for the other compounds were obtained. Detection limits were in the range of 0.1?C0.32???g?L^?1. Single fiber repeatability and fiber to fiber reproducibility were less than 8.9 and 15.8%, respectively. Seawater sample was analyzed as real sample and good recoveries (81?C108%) were obtained for target analytes.     

I. Spectroscopic Investigation of Charge Transrer Complexes of Oxime Intermediates Prepared from Some Pharmaceutical Carbonyl Compounds

Spectroscopic studies on the reaction of iodine as π-acceptor and chloronil as π-acceptor with oxime intermediates prepared from certain pharmaceutical carbonyl compounds are reported. These compounds include Δ^1,4 -3-corticosteroids (prednisone, prednisolone, dexamethasone), Δ⁴-3-ketosteroids (progesterone, testosterone propinate, nandrolone phenpropionate), griseofulvin, carvone, and menthone. The spectroscopic techniques applied are IR, far IR spectroscopy, H¹, C¹³NMR, mass spectra (MS), fast atom bombardment mass spectra (FABMS), electron spin resonance (ESR) and microanalysis of the reaction products. The structure elucidation studies of these complexes confirmed the charge transfer complex (CTC) formation.     

Investigating the possibility of increasing cooling air flow in a hydrogenerator rotor fan

Journal of Thermal Analysis and Calorimetry - The possibility of increasing cooling airflow inside a hydrogenerator rotor fan is investigated. The rotor fan has a heat dissipation problem and it is...     

Synthesis and biological evaluation of a novel 99mTc‐cyclopentadienyltricarbonyl technetium complex as a new potential brain perfusion imaging agent

A new cytectrene prototype of general formula RCpTc(CO)₃ (R = C₆H₅NHCO, Cp = cyclopentadienyl moiety) has been synthesized from N‐phenylferrocenecarboxamide 2 , characterized and evaluated as a potential brain perfusion imaging agent. An improved procedure has been developed to obtain both the ligand 2 , characterized by its solid‐state structure (orthorhombic, Pccn, a = 10.4443(2) Å, b = 26.1467(6) Å, c = 9.9977(3) Å), and the corresponding metallic Tc‐ and Re‐complexes in good yield. These latter complexes possessed similar HPLC retention times, thereby indicating identity of their molecular structures. The Tc‐complex ^99m Tc‐2 is lipophilic enough to cross the blood‐brain barrier. This complex exhibits good brain uptake (1.41% injected dose per gram tissue at 5 min) combined with a fairly good retention of radioactivity in brain (0.48% injected dose per gram tissue after 1 h). Then, the distribution of the activity at 5 min post‐injection in various rat brain regions showed a higher accumulation in the hippocampus area. The new ^99mTc‐cyclopentadienyltricarbonyl technetium complex reported here showed promising biological results, making it an interesting base for the development of a new generation of cytectrene as brain perfusion imaging agent. Copyright © 2011 John Wiley & Sons, Ltd.     

The effect of electric field geometry on the performance of electromembrane extraction systems: Footprints of a third driving force along with migration and diffusion

The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m⁻¹ and 111 kV m⁻¹ in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form.     

Stereological study of the effects of nandrolone decanoate on the rat prostate

It has been shown that nandrolone decanoate which is one of the anabolic-androgenic steroid compounds changes the testis structure and sperm quality but quantitative studies of the prostate have received less attention. Control rats received the peanut oil and experimental group received nandrolone decanoate for 14 weeks. Then the rats were left untreated for 14 weeks. After 14 weeks of withdrawal, the prostate was studied using stereological methods. The mean prostate weight decreased approximately 39% (p<0.009) in nandrolone decanoate treated rats. The mean total prostate volume, glands, epithelia, fluids and collagen bundles reduced approximately 30% (p<0.03), approximately 31% (p<0.03), approximately 41% (p<0.02), approximately 31% (p<0.05) and approximately 59.5% (p<0.02) in the experimental group. The mean total luminal surface of the glands and total length of the vessels decreased approximately 40% (p<0.02) and approximately 46% (p<0.009), respectively, in the nandrolone decanoate treated rats. The height of epithelium did show no difference. It can be concluded that nandrolone decanoate causes atrophic changes in the components of rat prostate.     

Stereological study of the effects of nandrolone decanoate on the mouse liver

BackgroundThe beneficial potential of anabolic steroids comes with undesirable side effects. Short and long term side effects have been demonstrated in many organs, and the liver changes are associated with androgenic anabolic steroids use. Despite the widespread physiological, biochemical and pathological investigation of the effects of androgenic anabolic steroids on the liver, the stereological study of the effects of anabolic androgenic steroids on the liver histological structure has received less attention.AimsThe present study investigates the nandrolone decanoate (ND) effects, on the liver.MethodsThe liver of the control and ND-treated mouse was fixed, processed, stained and studied using modern stereological methods.ResultsThe analysis of the data revealed that liver weight and volume increased ～19% and ～35%, in ND-treated group in comparison with the control group respectively. The total volume of the hepatocytes and sinusoids increased ～59% and ～116% respectively in treated animals. The total volume of the central veins and portal triad veins decreased ～42% and ～70%, respectively. The total number of hepatocytes nuclei in experimental group increased ～20%. The mean total volume of the connective tissue, arteries and bile ductules in the portal tracts and the mean volume of the hepatocytes and their nuclei did not show any significant changes.ConclusionND can increase the volume of the liver, mainly due to hyperplasia of the hepatocytes.     

An environmentally friendly electrochemical method for synthesis of benzofuranoquinone derivatives

Electrochemical oxidation of catechols (1a-c) has been studied in the presence of 2-hydroxy-1,4-naphtoquinone (3b) in aqueous solutions, using cyclic voltammetry and controlled-potential coulometry. The results indicated that the electrochemically generated o-benzoquinones (2a-c) participate in Michael addition reaction with 3b to the corresponding benzofuranoquinones (8a-c, 10a-c). The electrochemical synthesis of these compounds has been successfully preformed at a carbon rod electrode with good yields using an environmentally friendly method.     

Straightforward Regio- and Diastereoselective Synthesis,Molecular Structure,Intermolecular Interactions and Mechanistic Study of Spirooxindole-Engrafted Rhodanine Analogs

Straightforward regio- and diastereoselective synthesis of bi-spirooxindole-engrafted rhodanine analogs 5a–d were achieved by one-pot multicomponent [3 + 2] cycloaddition (32CA) reaction of stabilized azomethine ylide (AYs 3a–d) generated in situ by condensation of L-thioproline and 6-chloro-isatin with (E)-2-(5-(4-chlorobenzylidene)-2,4-dioxothiazolidin-3-yl)-N-(2-morpholinoethyl)acetamide. The bi-spirooxindole-engrafted rhodanine analogs were constructed with excellent diastereo- and regioselectivity along with high chemical yield. X-ray crystallographic investigations for hybrid 5a revealed the presence of four contiguous stereocenters related to C11, C12, C19 and C22 of the spiro structure. Hirshfeld calculations indicated the presence of many short intermolecular contacts such as Cl...C, S...S, S...H, O...H, N...H, H...C, C...C and H...H interactions. These contacts played a very important role in the crystal stability. The polar nature of the 32CA reaction was studied by analysis of the conceptual DFT reactivity indices. Theoretical study of this 32CA reaction indicated that it takes place through a non-concerted two-stage one-step mechanism associated with the nucleophilic attack of AY 3a to the electrophilic ethylene derivative.